I do a colon tube all of the time because I want to be sure that the water gets to the cecum end of my bowel. I have found that I have to put in about 1-1/4 to 1-1/2 quarts using a nozzle of some kind in order to fill, stretch, and maybe straighten the lower end, or else the tube will not make it past the first and subsequent curves. Then I can put the tube in at least two feet, sometimes more, though I cannot say why it will go in four feet sometimes and only two and a half others.
What does it feel like. First, of course is the pleasure of putting the nozzle and, later, the tube in my anus. With the tube, it can take several minutes to work it slowly in all of the way. You need to move it in and out a couple of inches while slowly advancing it. As Susie says, move it like you are jacking off your husband. The first bend is about six inches in. then you will feel it passing through the bend and the descending colon, which might pleasure or hurt you, or both. You will feel a bit of a barrier as it goes around the corner to the transverse colon, and, again, you can feel it moving in your colon. Eventually, after two feet or so, it will not go in anymore and you stop pushing it.
I always put the nozzle in first and let in the quart or so of water. Then I take the nozzle out and hook up the tube, bleed all of the air out of it (important), and turn the water on as soon as the tip of the tube is inside of me. I usually have the water running all of the time I am pushing the tube in so that it does not get clogged, but you can try it with the water off if you wish. I fill myself with a total of four or a bit more quarts of water.
Be sure to lube your anus before putting the nozzle in, and again before putting the tube in. Just lubricating the nozzle or tube is not sufficient. Give it a try. You probably will not be successful on your first try, but if you keep trying, eventually you will get the hang of it and will have a high enema which will clean you out better than if you just used a nozzle.
Have a good time.
hankb